Incandescent electric lamp.



T; E. ROBERTSON. mcmnnscnm ELECTRIC LAMP.

APPLICATION FILED NOV. 2, 1908. I

973,703. a nted 0ct.25,19 10.

Inventor Thoma; 'E.Roberts6n,

THOMAS E. ROBERTSON, OF CATFORD, ENGLAND, ASIGNOR TO COMPANY A CORPORATION OENEW YORK.

GENERAL ELECTRIC INCANDESCENT ELECTRIC LAMP.

Specification of Letters Patent.

Patented Oct. 25, 1910.

Application filed November 2, 1908. Serial No. 480,565.

To all whom it may concern:

Be it known that I. THOMAS E. Ronsn'r- SON, a subject of the King of Great Britain, residing at Catford, Kent, England, have invented certain new and useful Improvements in Incandescent Electric Lamps, of which the following is a specification.

The present invention relates to incandescent electric lamps of the type having metallic filaments.

In lamps having filaments of tungsten, tantalum, and other highly refractory metals. it is necessary that the filament should be of considerable length in order to have the necessary resistance for operation at practical voltages, and since the filaments are necessarily long, special supporting means must be used to hold the filament in place.

According to my present- 'lIlVtElltiOll, the

filament loops are supported intermediate their ends by extensib e elastic anchors capable of transverse movement to compensate for unequal and abnormal expansion and contraction.

Embodiments of my invention are illustrated in the accompany ng drawing, in which Figure 1 shows a lamp with intermediate anchors pulling the filament legs toward the central pedestal; and Fig. 2 shows a modified form in which the filament logs are pulled outward toward the bulb of the lamp.

The lamp shown in Fig. l comprisesa central pedestal 1 about which a plurality of metal filament loops 2 are grouped. Each loop is welded or otherwise connected at its lower or free ends to current supply conductors 3 and is held in place at the opposite or looped end by supports 4., preferably resilient. Intermediate these end support mgmeans, I provide a number of spirals or 'other suitably shaped resilient anchors.

which are connected to the glass pedestal and are provided with. loops through which the filament legs pass. though they may be connected thereto by means of a pasted joint if desired. since it is immaterial whether the connection with the filament is rigid or not.

In the modification shown in Fig. 2, the reference numerals of which correspond with those of Fig. l. the intermediate supports or anchors 5 are connected to the lamp bull; or globe instead of to the glass pedestal.

It is well known that metallic filaments contract considerably after having burned a short time, and inasmuch as this contraction varies. greatly and in a somewhat uncertain manner, it has been found very diflicult hitherto to allow for this variation in contraction.

In a lamp constructed according to my invention, contraction of the filaments will cause the anchors 5 to expand or stretch out to a greater length, and thus allow'the filaments to straighten out somewhat. These intermediate anchors, being of a springy nature, will maintain the filaments at a proper tension Without danger of placing them under excessive strain.

When my invention is employed, it is not necessary that the end supports 4 be re silient. and the filaments may be rigidly held at their extremities; for provided they are not perfectly straight, the intermediate anchors will allow them to straighten as they contract. Moreover, if the filaments are rig dly connected with the anchors 5, or should the two weld together during normal operation, .the arrangement is such that should one portion of a filament contract or expand to a greater extent than the other portion, the anchor will compensate for this inequality by combined longitudinal and transverse movement.

Another important result of this arran 'ement is that the filaments are always under tension during transit. so that hammering oi the filaments upon their supports is pre vented and sudden shocks during transport are absorbed by the intermediate springs.

\Vhat I claim as new and desire to secure by Letters Patent of the United States. is,--

1. In an incandescent lamp, a filamentloop, suitable supportin means for the ends and the bend of said oop. and a resilient anchor engaging said loop intermediate its end and bend supports.

2. In an incandescent lamp, a filament loop, supports for the ends and the bend of said loop, and resilient anchors inter mediate said end and bend supports pulling the filament legs sidewise.

In an incandescent lamp. the combination of a central pedestal, a plurality of filament loops grouped about said pedestal.

supports for the ends and the bends of said loops, and resilient anchors maintainingsaid fi ament loops in tension.

4. In an incandescent lamp, thecombination of a filament loop, current supply conductors therefor, a resilient support for the bend of said loop, and resilient anchors be tween said support and said current supply conductors.

In an incandescent lamp, the combina tion of a filament extending between 21 current supply conductor and a support, and a resilient anchor situated intermediate said conductor and said support and maintain ing said filament in tension.

6. In an incandescent lamp., the combinw tion of a filament stretched between supporting means, and an intermediate resilient anchor engaging said filament and acting in a direction transverse thereto.

7. In an incandescent lamp the combination of a edestal stem, 21 pair of filainen't carriers suitably spaced apart on. said stem, :1 filament extending between said carriers, and. resilient anchor for the intenmediate portion of said filament.

8. In an incandescent lamp, the CUIIllJlLui tion of a pedestal stem, a pair of filament carriers suitably spaced apart on said stem, a filament extending between said carriers,

and a resilient anchor connected to said stein upon the ilament to Witnesses F. J. SKoYLEs, H. D. JAMESON. 

